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Report of the ILC-TRC Working Groupon
Technology, RF Power, and EnergyPerformance
Chris Adolphsen
International Linear Collider –Technical ReviewCommittee (ILC-TRC) Overview
History– Winter 2001: IFCA
Requests Second ILC-TRCReport (First Published in1995).
– Fall 2001: Working GroupsFormed.
– 2002: Working GroupsConvene Four Times toDefine Tasks, ReviewProgress and FormulateSummary.
– Jan. 2003: Complete Report
Organization– Chair: Gregory Loew (SLAC)
– Steering Committee• Reinhard Brinkmann (DESY)• Kaoru Yokoya (KEK)• Tor Raubenheimer (SLAC)• Gilbert Guignard (CERN)
– Working Groups• Technology, RF Power and Energy
Performance Assessments (Chair: DanielBoussard)
• Luminosity Performance Assessments(Chair: Gerry Dugan)
• Reliability, Availability, and Operability(Chairs: Nan Phinney, Ralph Pasquinelli)
Charge to the ILC-TRC
• To assess the present technical status of the four LC designs at hand,
TELSA, NLC/JLC-X, JLC-C and CLIC
and their potentials for meeting the advertised parameters at 500 GeVc.m. Use common criteria, definitions, computer codes, etc., for the
assessments.
• To assess the potential of each design for reaching higher energies
above 500 GeV c.m.
• To establish, for each design, the R&D work that remains to be donein the next few years.
• To suggest future areas of collaboration.
Contents of the Report
Not in the Report:
• Selection of ‘Best’ Design• Cost Comparisons• High Level Summary of
Strengths/Weaknesses of theDesigns
• Likelihoods that R&D Objectiveswill be Met
• Review of Electron-Electron orGamma-Gamma Options
Included in the Report (450 pages):
• Descriptions of the Four Machines at500 GeV c.m.– ‘Mega-tables’– Upgrade Paths to Higher Energies– Test Facilities and Other Project
R&D Programs• Working Group Assessments:
– Technology, RF Power andEnergy Performance
– Luminosity Performance– Reliability, Availability and
Operability• Summary of R&D that Remains to be
Done and Overall Assessments
Members of the Technology, RF Power andEnergy Performance Working Group
– Adolphsen, Chris - SLAC– Braun, Hans H. -CERN – Chin, YongHo - KEK – Edwards, Helen - FNAL – Hûbner, Kurt - CERN – Lilje, Lutz - DESY – Logatchov, Pavel - BINP – Pasquinelli, Ralph - FNAL– Ross, Marc - SLAC – Shintake, Tsumoru - KEK– Toge, Nobu - KEK – Weise, Hans – DESY– Wilson, Perry - SLAC
Sub-Groups:
• Technology of Injectors, Damping
Rings and Beam Delivery (H. Weise)• Power Sources: Klystrons, Power
Supplies, Modulators and Low Level
RF (Y.H. Chin)• Power Distribution: RF Pulse
Compression, Waveguides, Two-
beam (K. Hübner)• Accelerator Structures (P. Wilson)
Working Group Methodology
Ranking Criteria
• R1: R&D needed for feasibilitydemonstration of the machine.
• R2: R&D needed to finalizedesign choices and ensurereliability of the machine.
• R3: R&D needed beforestarting production of systemsand components.
• R4: R&D desirable for technicalor cost optimization.
• The groups assessed theirrespective systems and topicsfor all machines.
• They examined milestones.• They summarized their positive
reactions as well as theirconcerns.
• The concerns were translatedinto R&D they felt is needed tomitigate them.
• A great effort was then made torank the R&D issues accordingto certain criteria →
LC Designs / RF Technology
• ‘Mature’ Designs– TESLA, based at DESY
• 1.3 GHz Superconducting Technology– NLC, based at SLAC and JLC-X, based at KEK
• 11.4 GHz Normal-Conducting Technology
• ‘Conventional’ Design– JLC-C, based at Super Photon ring-8 GeV (SPring-8) and KEK
• 5.7 GHz Normal-Conducting Technology
• ‘Futuristic’ Design – Aimed for 3 TeV c.m.– CLIC, based at CERN
• Drive Beam Power Source• 30 GHz Normal-Conducting Linac Technology
• NLC/JLC-X: 1 TeV c.m.
– Fill second half of each tunnel with RF components.– Run with same linac beam parameters as 500 GeV operation. Linac
AC power doubles.
– Can increase to 1.3 TeV with lower beam current (lower luminosity).• TESLA: 800 GeV c.m.
– Run at 35 MV/m with 50% higher beam power (linac tunnel lengthremains the same).
– Requires doubling 2 K cooling capacity and number of klystrons andmodulators. Linac AC power increases by 50%.
• CLIC
– Lengthen linac and drive beam.– Drive accelerator requires proportionally higher modulator capacity,
cooling and AC power.
Energy Upgrades
R1 ‘Scorecard’: R&D Needed for a FeasibilityDemonstration of the Machine
Yes
No
No
No
Modulators
YesYesYesCLIC
YesYesNoJLC-C
YesYesNoNLC/JLC-X
No (500 GeV)Yes (800 GeV)
NoNoTESLA
AcceleratorStructures
RFDistributionKlystrons
NLC/JLC-X Structure Development (65 MV/m Unloaded Gradient Goal for 0.5 & 1 TeV Collider)
53 cm Traveling-Wave Structure Making Steady Process Toward an ‘NLC/JLC –
Ready’ Structure
Ø Recently Operated a Structure at 90 MV/m
with an Acceptable Trip Rate (1 per day).
Ø Currently Developing Structures with an
Acceptable Average Iris Radius from a
Wakefield Perspective.
Ø Still Need to Add Slots in Cells for Wakefield
Damping.
Summary of R2 Rankings (R&D Needed to FinalizeDesign Choices and Ensure Reliability of the Machine)
• RF Unit Tests– Assemble system of essential RF Unit components that at minimum
will power a single ‘feed’ of structures:• Modulator• Klystrons and Low Level RF• RF Distribution• Accelerator Structures (at least some with HOM damping).
– Run at nominal power (peak and average) with beam in a machine-like environment.
– Evaluate performance:• Breakdown, quench and failure rates.• Drive beam stability in case of CLIC.
• Technology– Develop fast (< 20 ns) kicker magnet for TESLA Damping Rings.
8 Klystrons, 8 Modulators,4 Three-Cell Coupled-Cavity Pulse Compressors
and 16, 1.8 m C-Band Structures(29 m of Accelerator)
SPring-8 Compact SASE Source
Highlights of the R3 and R4 Rankings
• R3: R&D needed before starting production of systems andcomponents.– Do long-term component testing to qualify lifetimes.– Develop more sophisticated low-level RF systems.
– Verify source laser stability.
• R4: R&D desirable for technical or cost optimization.– Continue fundamental studies of high gradient limitations.
– Develop less expensive, more reliable and more efficient RFcomponents.
– Evaluate feasibility of a helical-undulator based polarized positronsource.
Technology, RF Power and EnergyPerformance Summary
• Found no obvious show stoppers preventing implementation of any ofthe designs with enough resources, effort and time. However,– CLIC appears the furthest away.
– With limited resources, benefit by converging on a common design soon.
• Found no major surprises for energy and technology issues:– Feasibility demonstrations are still required: TESLA (for 800 GeV),
NLC/JLC-X and JLC-C are working to complete these in 2003.
– Major efforts underway to do system tests:
• TTF-2 for TESLA, which is also an FEL facility
• Eight-Pack/NLCTA for NLC/JLC-X
• SPring-8 Linac for JLC-C, which is primarily an FEL facility
• CTF3 for CLIC
• The TRC effort was great learning experience for all involved and thereport will be a valuable resource for selecting a linear collider design.